Large vehicles, particularly trucks and trailers, which do excessive amounts of highway driving require a clear field-of-view along both sides of the vehicle. This is particularly critical for the passenger side of the vehicle. The driver can always turn his head and look over his left shoulder to view objects alongside the left side of his vehicle, if necessary.
While driving in congested freeway trafic, and while transporting huge masses of material and traveling at speeds near to or exceeding the allowable speed limits, the driver must make decisions quickly concerning the movement of his vehicle based upon the information provided to him by these mirrors. It is critical that the driver have a full field-of-view of vehicles in adjacent lanes when it is necessary for his vehicle to change lanes. Although current laws generally require mirrors disposed along both sides of large vehicles, the size and shape of such mirrors vary considerably, providing the driver with a different field-of-view depending upon the mirror used.
U.S. Pat. No. 4,436,372, entitled "Elliptical Mirror for Vehicular Use", by W. P. Schmidt and F. D. Hutchinson, discloses a major advance in improving the field of view of drivers of large vehicles, such as school busses. By employing a pair of ellipsoidal mirrors on the front of the vehicle, blind spots around the vehicle can be substantially reduced.
A variation of this design is disclosed in patent application Ser. No. 254,027 referenced above, where the elliptical mirror of U.S. Pat. No. 4,436,372 is bisected along a horizontal axis generating a half-ellipsoidal surface. Since this surface is smaller than the full ellipsoidal mirror, the size of the blindspot behind the mirror is reduced. The top portion of the elliptical mirror that is removed when the surface is bisected generally discloses objects that are disposed over the driver. It is generally not necessary to view these objects to maneuver the vehicle.
However, there is a need for a rear-view mirror which provides an enlarged field-of-view of objects adjacent to and behind the vehicle, and which is not so large as to obstruct the driver's visibility of objects located behind the mirror.